using System;

using System.Collections.Generic;

public class Person {

  string _name = "";

    public Person(string gender){

        _name = gender + Guid.NewGuid().ToString().Remove(8);

    }

    public override string ToString(){

        return _name;   

    }

}

​

public class Program

{

    public static void Main()

    {

​

​

​

    //setup

​

    //hold the group sizes we want to make - you say your user chose this

    int[] groupSizes = new[] {3, 4, 4, 5, 5, 6};

​

    //you have lists of people from somewhere

    List<Person> boys = new List<Person>();

    for(int i = 0; i < 15; i++)

      boys.Add(new Person("boy"));

    List<Person> girls = new List<Person>();

    for(int i = 0; i < 12; i++)

      girls.Add(new Person("girl"));

​

    //logic of random grouping

    List<List<Person>> groups = new List<List<Person>>();

    Random r = new Random();

​

        bool b = false;

    //for each groupsize we make

    foreach(int g in groupSizes){ 

​

      List<Person> group = new List<Person>(); //new group

      for(int i = 0; i < g; i++){ //take people, up to group size

b=!b;

        //take boys and girls alternately

        var fr = b ? boys : girls;

​

        //if there are no more boys/girls, take other gender instead

        if(fr.Count == 0) 

          fr = b ? girls : boys;

        //choose a person at random, less than list length

        var ri = r.Next(fr.Count);

​

        //add to the current grouping

        group.Add(fr[ri]);

​

        //remove from consideration

        fr.RemoveAt(ri);

      }

      //group is made, store in the groups list

      groups.Add(group);

        Console.Out.Write("Group " + g + ":" + group.Count + " members= ");

        foreach(var p in group)

            Console.Out.Write(p.ToString() + " ");

        Console.Out.WriteLine();

    }

    }

}